Field of the Invention
The present invention relates generally to the field of sound reproduction, and more particularly to an improved system and related method for producing vibratory sensations on a listener's body which are similar to those experienced during a live performance, both in their vibratory nature and in their properly synchronized timing with the audible sounds which the listener is hearing at any given moment.
Electronic equipment for use in reproducing sound has improved dramatically with the quantum leaps made in the field of solid state electronics. Sound reproduction systems which are available today for even a modest price outperform the most elaborate and expensive systems of the recent past. When the listener closes his or her eyes, he or she can almost imagine that the sounds being listened to are not being electronically reproduced, but rather are occurring live in front (and indeed around) the listener. It is a fact that from the audible sound alone, it has become increasingly difficult to distinguish between a live performance and a digital recording reproduced on a high quality stereo system.
In fact, the only aspect distinguishing a live performance from such a high quality reproduction of the performance is not the sound, but rather is the "feel" of the live performance. By the term the "feel" it is meant that the vibratory aspects of a reproduced performance, even of a high quality reproduction, are just not the same. The "feel" of the sound on the listener's body is somehow different in a reproduced performance from the "feel" of the live performance of the same sounds in a manner which, while difficult to quantify, is nevertheless meaningful and significant.
The first assault on achieving the proper "feel" has resulted in the wide usage of subwoofers, which are able to better reproduce the low frequencies which digital recordings are able to record. Subwoofers move air, and are substantially nondirectional, and do result in an enhancement of the "feel" of a reproduced performance. However, they are limited in what they can achieve, and while having a subwoofer in a high quality sound reproduction system is better than not having a subwoofer in the same system, they still have not succeeded in capturing the proper "feel" of a live performance.
As might well be expected, the art is not without substantial efforts having been expended in the area of the reproduction of vibratory sensations which may be perceived by the body. In fact, the art is replete with devices for providing vibratory sensations to the body of an individual. While most of these references are not directly on point, it is nevertheless illuminating to briefly examine the art in this area.
Most of the references found in the art fall into one of two areas. The first of these two areas is the use of vibratory stimulation primarily for treatment in therapeutic applications; This area, while technically interesting, is less directly on point. The second of the areas, which is the more pertinent area, provides a vibratory stimulus to a listener in addition to providing a reasonable quality of audible sound reproduction.
The first of these areas is illustrated by U.S. Pat. No. 3,880,152, to Nohmura, U.S. Pat. No. 4,055,170, also to Nohmura, U.S. Pat. No. 4,813,403, to Endo, U.S. Pat. No. 5,035,235, to Chesky, U.S. Pat. No. 5,076,260, to Komatsu, U.S. Pat. No. 5,086,755, to Schmid-Eilber, and U.S. Pat. No. 5,101,810, to Skille et al. The two Nohmura references, the Schmid-Eilber reference, and the Skille et al. reference are all lounge chairs having speakers built into the chairs to provide therapeutic vibration in addition to music. All four are cited as promoting health through relaxation of the body.
The Chesky reference teaches a table rather than a lounge chair, but also has speakers built in for providing therapeutic vibration to a patient lying on the table. The Endo device uses a speaker to generate a vibratory sensation which is transmitted through a closed gas space to a vibratory member used to stimulate the human body. Finally, the Komatsu reference teaches an elaborate control system for generating a plurality of different types of vibratory signals. It is noteworthy that none of the devices in this first group are for use in addressing the problem discussed herein, namely producing a desired vibratory sensation to a listener in accompaniment with an audible signal.
The second area mentioned above is that of the systems which produce reasonable quality sound in addition to producing a vibratory stimulus. This area is illustrated by U.S. Pat. No. 4,023,566, to Martinmaas, U.S. Pat. No. 4,967,871, to Komatsubara, and U.S. Pat. No. 5,216,769, to Eakin. The Martinmaas device is a chair having a number of audio quality speakers located therein. The Komatsubara reference teaches a compact, portable chair having speakers built therein. Finally, the Eakin reference discloses a foldable bed having speakers built therein. Again, it is apparent from this second group of references that they do not address the problem of the present invention, namely the problem of how to add vibratory sensation to a reproduced performance.
Still another group of references teaches the use of transducers in contact with portions of the human body to conduct sound. One of these references, namely U.S. Pat. No. 4,322,585, to Liautaud, teaches the use of a transducer which is placed in contact with the bone to transmit sound. However, the Liautaud reference does not recreate the sensation of a live audible performance on the body, but rather merely uses a portion of the body to transmit sound. Similarly, the other reference in this group, U.S. Pat. No. 5,054,079 to Frielingsdorf et al., teaches the use of bone to conduct sound, this time from the body to a microphone.
Another group of references is illustrated by U.S. Pat. No. 4,635,287, to Hirano, U.S. Pat. No. 4,829,581, to Nieuwendijk et al., and U.S. Pat. No. 5,125,033, to Lee. The Hirano, Nieuwendijk al., and Lee references teach transducers for use in applications similar to those discussed above. The Hirano reference discloses a transducer for installation in the back of a seat, for example, and only reproduces low frequencies. The Nieuwendijk et al. reference describes a transducer for general use. The Lee reference teaches a body sense speaker for contact with the body in applications like a seat, a vest, or a belt. The references in this group also do not suggest a solution to the problem addressed by the present application.
Only one reference in the art addresses the problem addressed by the present invention: U.S. Pat. No. 4,064,376, to Yamada. The Yamada reference teaches a sound reproduction system using a speaker mounted away from the listener and a transducer mounted in a chair for providing a vibratory stimulus to the listener as he or she listens to sound reproduced by the remote speaker. Thus, Yamada seeks to enhance the audible sound with vibratory stimulus derived from the sound signal itself.
However, the Yamada reference does not address a key problem identified for the first time and addressed by the present invention. That problem is that sound and electrical signals travel at different speeds. Specifically, sound travels at 1140 feet per second, while electrical signals travel at 984 million feet per second. Thus, even at short listening distances, there is a significant difference in the propagation of sound as compared with the propagation of electrical signals.
Assume that a listener is located only twelve feet from a speaker producing an audible sound, and has the Yamada system used to provide a vibratory stimulus from the recorded sound signals. In this case, the vibratory signal will arrive earlier than the audible signals by one one-hundredth (0.01) of a second. This difference in timing is easily noticed by a human listener, who can sense the difference in the arrival times of sound waves at his or her ears which are less than one foot apart, or less than one thousandth (0.001) of a second apart. This ability is utilized to identify the direction of a sound source, and is commonly used in stereo systems. The lack of synchrony in the vibration produces a perceived irritation similar to the visual irritation of watching a movie in which the lips are not closely synchronized with the dialogue. Thus, the Yamada reference, while still representing an improvement over the art, is not without a significant defect which will prevent the Yamada system from achieving the effects of a live performance.
It is accordingly the primary objective of the apparatus and method of the present invention that they produce a vibratory sensation affecting the listener which is properly synchronized with the audible sound heard by the listener to thereby produce a result which is perceived as pleasing. In this regard, it is a related objective that the apparatus and method of the present invention allow the precise matching of the vibration and the audible sound at varying distances between the source of the audible sound and the listener, thereby allowing the listener to customize the result to fit any possible situation or location. This variable coupling of the propagation times of the sound between the sound source and the ears of the listener on the one hand and the vibration supplied to the listener's body on the other hand must be easily adjustable by the listener to allow custom tailoring of the system and method of the present invention to fit a wide variety of different ambient conditions and locations.
It is a further objective of the present invention that it provide an enhanced degree of coupling between a transducer producing the vibratory sensation and the portion(s) of the human body being stimulated. As such, it is an objective that the device and method of the present invention provide stimulation to a wide area of the human body to avoid a sensation of only a small area of the human body being prodded or otherwise unnaturally stimulated. Specifically, it is an objective of the present invention that it stimulate a sufficiently large area of the human body to realistically simulate the vibratory stimulation of a live performance on the human body. Tests of the present invention have established that an area on the order of half of the span of the human body area generally to be contacted should be closely coupled to the vibratory stimulation for best results. It is thus a related objective that the preset invention have an enhanced degree of coupling between the transducer and the human body of a character not found in the art, where vibrating chairs otherwise proliferate.
A particular benefit of the apparatus should be to provide the "feeling" of music, which many others have tried to achieve, sometimes through the use of excessive acoustic levels which can cause hearing loss, thereby permanently damaging the ears in some cases.
The vibratory producing and coupling apparatus of the present invention must also be of construction which is both durable and long lasting, and it should also require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of the vibratory producing and coupling apparatus of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the apparatus and method of the present invention be achieved without incurring any substantial relative disadvantage.